Aerosol Generating System

ABSTRACT

An aerosol generating system includes a consumable having a rod-shaped portion containing aerosol generating substrate; a heating chamber having a first end, a second end and a side wall extending around the heating chamber between the first and second ends, the heating chamber being configured to receive the rod-shaped portion of the consumable; and a heater configured to deliver heat to the heating chamber from the side wall, wherein: a width of the chamber is greater than a width of the rod-shaped portion, the consumable includes a resilient portion around a length axis of the rod-shaped portion, the heating chamber further includes a plurality of inward protrusions extending from the side wall and distributed around an inner perimeter of the heating chamber, and the protrusions are configured to engage with and apply pressure to the resilient portion in order to position the consumable within the chamber.

TECHNICAL FIELD

The present disclosure relates to an aerosol generation system in which an aerosol generating substrate is heated to form an aerosol. The disclosure is particularly applicable to a portable aerosol generation device, which may be self-contained and low temperature. Such devices may heat, rather than burn, tobacco or other suitable aerosol substrate materials by conduction, convection, and/or radiation, to generate an aerosol for inhalation.

BACKGROUND

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. Various devices and systems are available that heat or warm aerosolisable substances as opposed to burning tobacco in conventional tobacco products.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generation device or heat-not-burn device. Devices of this type generate an aerosol or vapour by heating an aerosol substrate that typically comprises moist leaf tobacco or other suitable aerosolisable material to a temperature typically in the range 150° C. to 350° C. Heating an aerosol substrate, but not combusting or burning it, releases an aerosol that comprises the components sought by the user but not the toxic and carcinogenic by-products of combustion and burning. Furthermore, the aerosol produced by heating the tobacco or other aerosolisable material does not typically comprise the burnt or bitter taste resulting from combustion and burning that can be unpleasant for the user and so the substrate does not therefore require the sugars and other additives that are typically added to such materials to make the smoke and/or vapour more palatable for the user.

In such devices, the aerosol substrate is often provided in a consumable containing a limited quantity of aerosol generating substrate, and able to generate a limited quantity of aerosol. It is desirable to increase the aerosol yield for a given amount of substrate.

SUMMARY

According to a first aspect, the present disclosure provides an aerosol generating system comprising: a consumable comprising a rod-shaped portion containing aerosol generating substrate; a heating chamber comprising a first end, a second end and a side wall extending around the heating chamber between the first and second ends, the heating chamber being configured to receive the rod-shaped portion of the consumable; and a heater configured to deliver heat to the heating chamber through the side wall, wherein: a width of the chamber is greater than a width of the rod-shaped portion, the consumable comprises a resilient portion around a length axis of the rod-shaped portion, the heating chamber further comprises a plurality of inward protrusions extending from the side wall and distributed around an inner perimeter of the heating chamber, and the protrusions are configured to engage with and apply pressure to the resilient portion in order to position the consumable within the chamber.

By providing a chamber having a width greater than the width of the rod-shaped portion, the consumable can be more easily inserted into the chamber.

However, the heater does not heat the heating chamber entirely uniformly. As a result, leaving the consumable loose within the wider chamber can reduce efficiency of heating and aerosol generation. By providing inward protrusions configured to engage with the consumable, the consumable can be held in a preferred position for being heated.

Furthermore, by configuring the protrusions to apply pressure to a resilient portion, this prevents the consumable from deforming, disengaging from the protrusions, and moving away from the preferred position.

Yet further, by applying pressure to a resilient portion around a length axis of the rod-shaped portion, the protrusions simultaneously apply pressure to at least a part of the aerosol generating substrate. This compression of the substrate improves aerosol generation efficiency.

The protrusions may be sized such that a space between the protrusions in the chamber is smaller than a width of the resilient portion. As a result, the resilient portion is compressed to fit between the protrusions.

Optionally, the protrusions are configured symmetrically relative to the length axis to assist positioning of the consumable at a center of the chamber.

Positioning the consumable at a center of the chamber is suitable for embodiments where the heater is disposed symmetrically around the side wall in order to improve efficiency of delivering heat to the heating chamber. Positioning the consumable at a center of the chamber also makes the system more intuitive to use, because the user inserts the consumable into the chamber the same way regardless of an orientation of the heating chamber around its length axis.

Optionally, the first end of the heating chamber is open to receive the rod-shaped portion and the second end of the heating chamber is closed.

In the case of a heating chamber which is only open at one end, the protrusions have a secondary advantage of providing a space between the consumable and the side wall of the heating chamber which can act as an air inlet for a user or a pump to draw air into the consumable at one end and extract the generated aerosol from another end of the consumable.

Optionally, when the resilient portion is compressed perpendicular to the length axis of the rod shape by a force of 0.4N, the consumable exhibits a strain ratio of below 10%.

More preferably, when the resilient portion is compressed perpendicular to the length axis of the rod shape by a force of 0.4N, the consumable exhibits a strain ratio of between 1% and 8%.

Optionally, when the resilient portion is compressed perpendicular to the length axis of the rod shape by a force of 8N, the consumable exhibits a strain ratio of below 15%.

More preferably, when the resilient portion is compressed perpendicular to the length axis of the rod shape by a force of 8N, the consumable exhibits a strain ratio of between 5% and 14%.

These parameters provide a consumable which is sufficiently firm to remain engaged with the protrusions in a preferred position for being heated. However, if the consumable is excessively firm, it can be difficult to insert the consumable at all.

Optionally, the rod-shaped portion comprises a wrapper surrounding the substrate, and the resilient portion comprises a portion of the wrapper.

By providing a wrapper that is at least partly resilient, the consumable can better maintain its shape when in the heating chamber, improving air flow through the consumable and generation of the aerosol.

Optionally, the wrapper comprises cellulose paper. In an alternative, the wrapper comprises cellulose paper layered with aluminium foil.

Optionally, the substrate comprises tobacco.

Optionally, the substrate comprises randomly oriented tobacco strands containing tobacco powder and an aerosol former. The tobacco strands may be obtained by cutting tobacco sheets obtained by paper forming, extrusion or casting.

Randomly oriented tobacco strands have been found to provide a more firm, or more uniformly firm, rod-shaped portion than is the case when the aerosol generating substrate comprises gathered tobacco sheets.

Optionally, the substrate density is between 0.3 mg/mm³ and 0.6 mg/mm³.

The inventors have found that increasing the substrate density, measured as a mass per unit volume within the wrapper, increases the firmness of the rod-shaped portion, especially when the substrate comprises the randomly oriented tobacco strands, while excessive density can lead to inefficient aerosol generation.

Optionally, the substrate comprises between 60 and 85 wt. % of tobacco lamina and between 8 and 20 wt. % of aerosol former and between 5 and 15 wt. % of filler, based on the total weight of the substrate.

Optionally, the substrate is a compressed tobacco substrate having soft granular texture or a mousse.

Optionally, the heater is configured to heat the interior of the heating chamber to at least 190° C.

More preferably, the heater is configured to heat the interior of the heating chamber to between 230° C. and 260° C.

Optionally, wherein the heater is configured to maintain the interior of the heating chamber at at least, preferably above 190° C., most preferably above 200° C., throughout a full puff sequencing time.

When the substrate comprises tobacco, the aerosol is a nicotine aerosol. The inventors have found that the above particular tobacco density ranges, forms of the tobacco, and heating profiles substantially improve a quantity of nicotine which can be generated from a given amount of substrate when pressure is applied to the substrate via the protrusions extending from the side wall of the heating chamber.

Optionally, the protrusions are ribs extending along the side wall, such that the ribs extend parallel to the length axis of the rod-shaped portion when the rod-shaped portion is received in the heating chamber.

Optionally, the substrate is arranged in a predetermined section of the rod-shaped portion extending along the length axis, and a length of the ribs is at least 50% of a length of the predetermined section.

More preferably, the length of the ribs is between 60% and 70% of the length of the predetermined section.

Consumables commonly contain sections in addition to a substrate section. For example, consumables may contain an air chamber or one or more filter sections. These sections do not need to be heated efficiently by the heater. On the other hand, a predetermined section containing the substrate is preferably subjected to pressure along its length to improve efficiency of heating and aerosol generation. By extending the ribs along a significant portion of the predetermined section, aerosol generation efficiency can be substantially improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic cross-sections of aerosol generating systems, in a plane including a length axis;

FIG. 2 is a schematic block diagram illustration of an aerosol generating device;

FIG. 3 is a schematic cross-section of a heating chamber, in a plane including the length axis;

FIG. 4 is a schematic cross-section of an aerosol generating system, perpendicular to the length axis;

FIGS. 5A and 5B provide a schematic illustration of a strain measurement for a consumable;

FIGS. 6 to 8 are schematic cross-sections of further aerosol generating systems, perpendicular to the length axis;

FIG. 9 is an example temperature profile for the heating chamber when generating an aerosol.

DETAILED DESCRIPTION

FIG. 1A is a schematic cross-section of an aerosol generating system embodying the invention.

Referring to FIG. 1A, a consumable 1 is located within an aerosol generating device 2 in order to generate an aerosol.

The consumable 1 comprises a rod-shaped portion 11, a resilient portion 12 around a length axis of the rod-shaped portion 11 and a filter 14.

The rod-shaped portion 11 contains aerosol generating substrate. The aerosol generating substrate is a material which, when heated, generates an aerosol. The aerosol may be passively allowed to dissipate from the aerosol generating system, but is preferably drawn out of the consumable 1 by air flow through the filter 14.

The aerosol generating substrate which may, for example, comprise tobacco or nicotine. The substrate may be a solid block, or may be loose material packed in a wrapper 13. Preferably the substrate comprises randomly oriented tobacco strands containing tobacco powder and an aerosol former. Suitable aerosol formers include: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as monohydric alcohols, acids such as lactic acid, glycerol derivatives, esters such as triacetin, triethylene glycol diacetate, triethyl citrate, glycerin or vegetable glycerin. In some embodiments, the aerosol generating agent may be glycerol, propylene glycol, or a mixture of glycerol and propylene glycol.

Tobacco strands may be obtained by, for example, mixing the tobacco powder and the aerosol former, drying the mixture in sheets, and shredding the sheets. A substrate density is preferably between 0.3 mg/mm³ and 0.6 mg/mm³.

The substrate density represents the mass of the substrate per volume unit in the rod-shaped portion. For randomly oriented tobacco strands, the substrate density can be controlled by adjusting the density of the tobacco sheet during production and by adjusting the filling rate of the strands in the rod-shaped portion. For example, the tobacco sheets have a density of 0.45 mg/mm³ and a filing rate of strands is 75% provides a substrate density of 0.337 mg/mm³.

The tobacco sheet may be paper reconstituted tobacco sheet, extruded tobacco sheet or cast tobacco sheet.

In one example, the substrate comprises between 60 and 85 wt. %, preferably between 70 and 80 wt. % tobacco lamina and between 8 and 20 wt. %, preferably between 10 and 18 wt. % of aerosol former, based on the total weight of the substrate. The substrate may further comprise a filler such as cellulose pulp. The substrate may comprise between 2 and 20 wt. %, preferably between 5 and 15 wt. % of filler. The substrate may further comprise flavour component. The flavour can be added as shreds to the substrate.

The resilient portion 12 is a portion of the consumable which resists deformation when external pressure is applied (in other words, it requires a force to deform the resilient portion 12 and the resilient portion 12 relaxes to a default shape when a force is no longer applied). The resilient portion 12 may take the form of a reinforced section of the wrapper 13, where the wrapper is thicker or made from a different material compared to the bulk of the wrapper, such as cardboard or metal. In some cases, the wrapper may comprise a first layer extending along the length axis, and a second layer located only at the resilient portion 12. Alternatively, the resilient property of the resilient portion 12 may be provided by the rod-shaped portion 11. For example, randomly oriented tobacco strands may be packed within a wrapper to provide a springy material. In some embodiments, the resilient portion 12 may be a complex structure including some internal voids and may have some initial give or looseness in which the portion deforms non-resiliently, before behaving resiliently when compressed beyond the initial give.

The wrapper 13 may, for example, comprise paper, a combination of paper aluminium foil, cardboard, or any material suitable for storing an aerosol generating substrate and allowing the substrate to be heated in the heating chamber. For example, the wrapper can be paper with air permeability 0-50 CU, basis weight of 25-80 g/m² and thickness 30-80 μm with or without aluminium foil of 20-30 μm thickness. In a preferred example, the paper has a basis weight between 35 and 50 g/m² and a thickness between 40 and 60 μm. The wrapper 13 may be omitted in embodiments where the substrate is self-supporting, for example where the substrate is a compressed tobacco substrate having soft granular texture such as described in co-pending applications EP 19209350.8 entitled “crumbed tobacco substrate” or EP 19209346.6 entitled “hot pressed tobacco substrate”. The substrate may also be a mousse comprising tobacco material, an aerosol former, a foam stabilizing agent, a foam forming agent, such as described in WO2016122375 or WO2020002607.

The aerosol generating device 2 comprises a heating chamber 21 and a heater 22.

The heating chamber 21 is a tubular structure with an internal hollow in which the consumable 1, or the rod-shaped portion 11 of the consumable 1, may be received. Specifically, the heating chamber comprises a side wall extending between a first end 212 and a second end 213. The first end 212 is open, or openable in use, in order to allow the rod-shaped portion 11 to be inserted. The second end 213 may be open as shown in FIG. 1A, in order to provide an air inlet for air to flow through the consumable. Alternatively, the second end 213 may be closed in order to improve heating efficiency of the heating chamber 21.

The heating chamber 21 may be formed from ceramic or metal. For example, the heating chamber 21 may be formed by bending or stamping sheet metal. In a preferred method, the heating chamber 21 is formed by deep drawing comprising: forming a metal disk blank it into an initial metal cup, annealing under vacuum or inert gas; and deep drawing the initial metal cup into an elongated tubular cup with a reduced tubular wall thickness as described in co-pending patent application EP 19196023.6 entitled “heating chamber”.

The heater 22 may be any heater suitable to deliver heat into the internal hollow of the heating chamber 21 through its side wall. For example, the heater 22 may be a planar heater attached to a flexible support and wrapped around the side wall of the heating chamber 21. Such a planar heater may be in the form of a resistive track driven by electricity, and the support may be one or more plastic or polymer sheets, for example a polyimide, a fluoropolymer such as PTFE, or a polyetheretherketone (PEEK). Alternatively, other types of heater may be used such as ones in which heat is provided by a chemical reaction such as fuel combustion. The heating chamber may further be surrounded by a heat insulator such as a vacuum tube, heat insulation fibre and/or aerogel.

Although the heater 22 is shown outside the heating chamber 21 in FIG. 1A, the heater 22 may in some embodiments be arranged inside the heating chamber 21. This would allow use of a thermally-insulating material for the side wall of the heating chamber 21. For example, one or more blade-type or pin-type heater(s) 22 may be designed to fit with one or more voids in the rod-shaped portion 11 of the consumable 1.

As shown in FIG. 1A, the heating chamber 21 has a greater width than the rod-shaped portion 11, in a direction perpendicular to a length axis of the rod-shaped portion 11. The gap formed between the heating chamber and the rod-shaped portion allows sufficient air to flow from the open first end 212 or second end 213 to the rod-shaped portion for extraction of the aerosol from the aerosol generating substrate. This also means that an end of the rod-shaped portion 11 can be more easily inserted into the heating chamber 21 without requiring precise alignment before or during insertion.

However, in order to heat the rod-shaped portion 11 efficiently for aerosol generation, an expected temperature distribution within the heating chamber 21 must be taken into account and the rod-shaped portion 11 must be precisely positioned within the heating chamber 21 to make more efficient use of this heat distribution. In order to position the consumable within the chamber 21, a plurality of inward protrusions 211 are configured to extend from the side wall of the heating chamber 21.

When the rod-shaped portion 11 is in the chamber 21, the protrusions 211 engage with and apply pressure to the resilient portion 12 in order to position the consumable securely within the chamber 21 at a position where it can be heated with greater efficiency.

For example, when the heater 22 is configured to supply heat symmetrically through the side wall of the chamber 21 (e.g. the heater extends around the whole of the chamber 21 or comprises symmetrically arranged heater portions), the protrusions 211 may similarly be configured symmetrically relative to the length axis (i.e. around the length axis on an inner perimeter of the heating chamber 21) in order to assist positioning the consumable at a center of the chamber. In this context, “at a center” means substantially near the center in terms of the width of the chamber 21.

As shown in FIG. 1A, the protrusions 211 may take the form of ribs extending along the side wall, parallel to the length axis of the rod-shaped portion 11. The ribs may be tapered towards the first end 212 of the heating chamber 21, in order to guide the consumable into a preferred position for heating.

One advantage of ribs extending along the side wall is that the resilient portion 12 can be easily aligned with the protrusions 211 along the length axis of the rod-shaped portion 11, without requiring the user to precisely position the consumable 1 along the length axis.

As an alternative, shown in FIG. 1B, the protrusions 211 need not extend along the side wall parallel to the length axis of the rod-shaped portion 11. Instead, the resilient portion 12 may extend along a substantial part of the rod-shaped portion 11, such that there are a wide range of positions along the length axis in which the protrusions 211 engage with the resilient portion 12. Such shorter protrusions 211 may be thin enough to bend in the length axis direction, as a substitute for the tapering of the ribs, in order to guide the consumable to a preferred position.

FIG. 2 is a schematic block diagram illustration of an aerosol generation device 2 having a heating chamber 21 and heater 22 as described above.

The aerosol generation device 2 of this example is a self-contained portable device having a power supply 24 and a controller 23 for controlling at least the heater 22. Preferably, the power supply and controller are an electrical power supply and an electronic controller, although the controller could in some embodiments be as simple as a physical switch, and the power supply could be a fuel supply in the case where the heater uses fuel combustion.

In the preferred embodiment where the controller 23 is an electronic controller, the device 2 may additionally comprise one or more thermistors for determining a temperature of the heater 22 or heating chamber 21.

The controller 23 may be configured to control the heater 22 in order to heat the interior of the heating chamber according to a predetermined temperature profile.

Preferably, where the aerosol generating substrate comprises tobacco, the heater 22 is controlled to heat the interior of the heating chamber 21 to at least 190° C., and more preferably between 230° C. and 260° C., for aerosol generation.

Additionally, the heater 22 is preferably controlled to maintain the interior of the heating chamber at at least 190° C., preferably above 200° C., for a predetermined puff sequencing time in which enough aerosol can be generated for a user to inhale a puff of aerosol. The puff sequencing time depends upon the particular aerosol generating substrate, and can be configured by testing the aerosol composition produced with different puff sequencing times, but has been found to be suitably at least four minutes in some cases. In other embodiments, rather than setting a predetermined puff sequencing time, the length of time for which the temperature is maintained may additionally or alternatively be based on a predetermined number of puffs of aerosol to be inhaled by a user. Puffs can be detected by, for example, detecting a temperature drop when ambient air is drawn into the heating chamber to replace heated, aerosol-rich air.

As shown in FIG. 2 , the device 2 additionally preferably comprises a lid 25 to keep the heating chamber 21 closed and protected when not in use. The lid 25 may, for example, be a sliding lid constrained by a rail to move between closed and open positions.

FIG. 3 is a schematic cross-section of a heating chamber 21 in a specific embodiment of an aerosol generating system. A consumable 1 is also partly illustrated located in heating position in the heating chamber 21.

As shown in FIG. 3 , the protrusions 211 may correspond to indentations 214 on an exterior surface of the heating chamber 21. In such cases, material need not be added to the side wall in order to form the protrusions 211, and instead the protrusions 211 can be formed by deforming the side wall. As a result of a thinner wall at the indentations, heat can be more efficiently transferred by conduction to the consumable at the indentations in addition to heat transferred by convection in the gap formed between the indentations or past the indentations.

In this specific embodiment, the second end 213 of the heating chamber 21 is closed, and air flow for drawing aerosol from the consumable is illustrated using arrows F1, F2 and F3. Air enters the heating chamber 21 at the first end 212 where the consumable 1 is spaced away from the side wall of the heating chamber 21. This space is defined by the protrusions 211, which position the consumable 1 within the chamber 21. Thus, an additional benefit of the protrusions 211 is that they support an air flow channel for air to be drawn through the consumable 1. After passing along the air flow channel supported by the protrusions 211, the air flows into the consumable 1 at an end adjacent to the second end 213 of the heating chamber 21. The air then flows through the rod-shaped portion 11 comprising the aerosol generating substrate and picks up the generated aerosol, flowing out of the consumable at arrow F3. The consumable 1 may comprise a space 15 for air to cool, and may comprise a filter 14. The space may advantageously be formed by a hollow paper tube. The filter 14 may advantageously be formed or two segments; one of which may be a hollow filter segment and the other may be a plain filter segment. The segments may be individually wrapped by plug wraps and combined by a common plug wrap to form the filter. The paper tube, filter and rod-shaped portion can be combined by a single or double layer of tipping paper. Ventilation holes may be formed, e.g. by lasering, through the wrapper, preferably through the paper tube and tipping paper in the close vicinity of the filter, for example at 1-2 mm distance.

Alternatively, where the consumable 1 is not configured for a user to directly inhale the aerosol from the consumable, the consumable 1 may comprise only the rod-shaped portion 11, and the aerosol-carrying air at arrow F3 may be further drawn through a structure of the aerosol generating device 2 to a reusable or semi-disposable mouthpiece of the aerosol generating device 2, separate from the consumable 1.

Preferably, the heating chamber 21 also comprises a platform 215 extending into the internal volume of the heating chamber 21 at the second end 213. The longer width of the platform is preferably smaller than the width of the consumable. The platform 215 promotes air flow by supporting the consumable 1 at least partly separated from the second end 213, as shown in FIG. 3 .

As shown in FIG. 3 , the protrusions 211 may partly compress the rod-shaped portion 11, in addition to engaging with the resilient portion 12. The rod-shaped portion need not be resilient along a whole contact area with the protrusions. Compressing the aerosol generating substrate in the rod-shaped portion 11 has the effect of improving aerosol generation for a given temperature profile. Hence, improved aerosol generation is a further benefit of the protrusions 211.

A length L1 of the rod-shaped portion 11 can be compared with a length L2 of the ribs 211 (i.e. a length of the protrusions 211 parallel to a length axis of the rod-shaped portion 11). For visual convenience, one end of the ribs 211 is aligned with an end of the rod-shaped portion 11 (as represented in transversal dotted line 19), but this need not generally be the case. The length L2 is preferably as least 50%, more preferably between 60% and 70%, of L1 (or of the length of a predetermined section that contains aerosol generating substrate, if this is not the whole length L1 of the rod-shaped portion 11), in order to substantially improve aerosol generation by compressing the aerosol generating substrate.

FIG. 4 is a schematic cross-section of an aerosol generating system similar to that shown in FIG. 3 , in a plane through the protrusions 211 and perpendicular to the length axis of the rod-shaped portion 11. This plane corresponds to dashed line X1 in FIG. 3 .

As shown in FIG. 4 , four protrusions 211 are symmetrically distributed around an inner perimeter of a round heating chamber 21. The heater 22 is arranged to encircle the outside of the heating chamber 21, and supply heat symmetrically towards a center of the heating chamber 21. In this case, the resilient portion 12 of the consumable 1 is positioned in the center of the heating chamber 21 by the protrusions 211. Additionally, although the resilient portion 12 is round when uncompressed, when positioned in the heating chamber 21 the resilient portion 12 is deformed locally. This is because the space between ends of the protrusions 211 is smaller than a width of the resilient portion 12 when uncompressed.

The protrusions 211 have a rounded profile as may, for example, form when bending the side wall of the heating chamber 21 to form the protrusions 211. (The corresponding indentations 214 on the exterior surface of the heating chamber 21, as shown in FIG. 3 , are omitted for simplicity).

One specific example was constructed corresponding to the heating chamber and consumable shapes illustrated in FIGS. 3 and 4 . Referring to FIG. 3 , the rod-shaped portion 11 had a length L1 of 20 mm and a distance L2 along the length axis between the platform 213 and the near end of the ribs 211 was 8 mm. Referring to FIG. 4 , in the specific example, the rod-shaped portion had a width of 7.0 mm, and the heating chamber had a maximum internal diameter of 7.6 mm and four rounded protrusions of maximum radial length of 0.4 mm (as measured from the internal surface of the chamber.

As described above, the resilient portion 12 is a portion of the consumable which resists deformation when external pressure is applied. Such resistance to deformation may be measured by comparing the strain on the resilient portion 12 for a given applied force. FIGS. 5A and 5B provide a schematic illustration of a strain measurement for a consumable.

FIG. 5A illustrates a testing device 3 for applying a predetermined force on an object between two surfaces 31 and 32. The testing device 3 may for example be a clamp or a press. An actuator 33 applies predetermined force to one surface 31 and moves the surface 31 until the force is balanced by stress in the object, as shown in FIG. 5B.

As shown in FIGS. 5A and 5B, the resilient portion 12 starts with a width W1 perpendicular to the length axis of the rod-shaped portion 11. When a sample of 10-mm of rod-shaped portion including the resilient portion 12 is subjected to a predetermined force in the testing device 3 perpendicular to the length axis of the rod-shaped portion 11, at a speed of 50 mm/min, the resilient portion 12 has a width W2, exhibiting a strain ratio equal to (W1−W2)/W1.

Preferably for systems according to the invention, the resilient portion 12 exhibits a strain ratio (expressed in %) of below 10%, and more preferably between 1% and 8%, when subjected to compression by an applied force of 0.4N in the configuration shown in FIG. 5B.

Additionally or alternatively, it is preferable for the resilient portion 12 to exhibit a strain ratio of below 15%, and more preferably between 5% and 14%, when subjected to compression by an applied force of 8N in the configuration shown in FIG. 5B.

As a matter of example, the strain ratio is respectively of about 6% and 12% when a first consumable with paper wrapper and rod-shaped portion of reconstituted tobacco strands of about 0.3 substrate density was subjected to compression by an applied force of respectively 0.4N and 8N. The strain ratio is respectively of about 2.5% and 5.5% when a second consumable with paper and aluminium wrapper and rod-shaped portion of randomly oriented reconstituted tobacco strands tobacco of about 0.3 substrate density was subjected to compression by an applied force of respectively 0.4N and 8N. As a matter of comparison, the strain ratio is respectively of about 10% and 15% when a third consumable with paper wrapper and rod-shaped portion of gathered sheet of reconstituted tobacco about 0.65 substrate density was subjected to compression by an applied force of respectively 0.4N and 8N. The third consumable exhibits lower capacity to position itself centrally in the heating chamber with higher risks of misalignment.

FIG. 6 is a schematic illustration of an alternative aerosol generating system in which the heating chamber 21 has three protrusions 211 rather than four as in the above-described example. Additionally, rather than the rounded protrusions 211 shown in FIG. 4 , the protrusions of this alternative have straight sides. Depending on the technique used for manufacturing the heating chamber 21, this straight sides may be more straightforward to produce than curved sides. As illustrated in FIG. 6 , the positioning elements are nevertheless capable of engaging with the resilient portion 12 and positioning the consumable within the chamber. Additionally, as with the example of FIG. 4 , the resilient portion 12 is compressed where it engages with the protrusions 211 and bulges between the protrusions 211. However, in this case, the deformation is less localised and is spread around the surface of the resilient portion 12. More generally, the heating chamber 21 may have any number of protrusions 211 extending from the side wall and distributed around an inner perimeter of the heating chamber 21, and each of the protrusions 211 may have any surface shape in cross-section perpendicular to the length axis, in addition to taking different shapes parallel to the length axis as shown in FIGS. 1A and 1B.

FIG. 7 is a schematic illustration of an alternative aerosol generating system in which the heating chamber 21 and the resilient portion 12 are not round but is instead approximately square. In polygonal heating chambers, or generally heating chambers with a partly curved and partly flat side wall, the above-described advantages of protrusions 211 are equally applicable, as the consumable may be positioned and subjected to pressure for improved heating efficiency, improved aerosol generation, and air flow through the consumable. Equally, the resilient portion 12 need not be round in cross-section when uncompressed, and may take any shape that can be positioned using appropriately sized and located protrusions 211. In the example of FIG. 7 , the resilient portion 12 is rectangular when not compressed, and has four sides which are compressed where they engage with a protrusion 211, and which bulge between the protrusions 211, but the bulge portions are also constrained by corners of the rectangular shape formed in the resilient portion (for example corners in formed in the wrapper).

FIG. 8 is a schematic illustration of an alternative aerosol generating system in which the heater 22 is arranged on one specific side of a rectangular heating chamber 21. In such an asymmetrical configuration of the heater 22, positioning the resilient portion 12 in a center of the heating chamber 21 would not lead to the most efficient heating of the aerosol generating substrate, and the rod-shaped portion 11 is preferably positioned against the specific side of the heating chamber 21. In this case, only two protrusions 211 are included, and are arranged to extend inward from a side of the heating chamber 21 that opposes the specific side where the heater 22 is arranged. Furthermore, since the protrusions 211 only need to apply pressure in parallel towards the specific side, the protrusions can have a simple rectangular cross-section. More generally, it can be understood that the protrusions 211 may preferably take different distributions around an inner perimeter of the heating chamber 21 according to an expected temperature distribution based on the position of the heater 22 and the shape of the chamber 21.

As can also be seen in FIG. 8 , in this case the position of the resilient portion 12 between the two remaining sides of the heating chamber 21 is not as important because the heater 22 extends across the specific side. In such a case, the rod-shaped portion 11 may be allowed to freely move within the chamber, without being positioned unnecessarily by further protrusions 211 between the two remaining sides.

FIG. 9 is an example temperature profile for the heating chamber when generating an aerosol, where heating temperature (in Celsius ° C.) is shown on the y-axis and time is shown on the x-axis (in arbitrary units). The heating temperature may be measured at the heater 22 or the heating chamber, for example using a temperature sensor or using a thermistor property of the heater 22.

In this example, the aerosol generating session comprises a temperature rising stage t₁ in which the heating temperature is raised to at least an aerosol generation temperature T₂. A length of the temperature rising stage t₁ may be predetermined or may be until the aerosol generation temperature T₂ is reached. In another example, the temperature rising stage t₁ may continue until feedback from the temperature sensor 13 indicates that the aerosol generation temperature T₂ has been reached. The aerosol generation temperature T₂ is chosen based on the type of aerosol generating substrate, and is a temperature at which aerosol is generated by heating the aerosol generating substrate. As shown in FIG. 3 , the temperature of the heater is raised some way above the aerosol generation temperature T₂ and the aerosol generation temperature is a lower limit for aerosol generation. In an example where the aerosol generating substrate comprises tobacco and an aerosol former, it has been found that 190° C. is suitable as a value for T₂, and aerosol generation is improved by continuing to heat the aerosol generating substrate to between 230° C. and 260° C.

Then, a temperature maintaining stage t₂ occurs in which the heating temperature is maintained. Although the temperature is illustrated as flat, it is likely to vary around a desired temperature. For example, the temperature may be maintained using pulse width modulation (PWM) control of the heater. During this time, aerosol may be extracted from the aerosol generating substrate in one or more puffs. In the example where the aerosol generating substrate comprises tobacco and an aerosol former, it has been found that 4 minutes and 10 seconds is a suitable example length for t₂.

Finally, a temperature falling stage t₃ occurs in which the heating temperature is allowed to fall below the aerosol generation temperature T₂. In general the heater is not powered during the temperature falling stage, although controlling a rate of cooling may have advantages, for example with respect to cleaning out the heating chamber after use. A time length of the temperature falling stage t₃ is not generally constrained, and the temperature falling stage may in some cases be interrupted by the start of a next aerosol generating session. However, a minimum time length t₃ may be set in some embodiments, the minimum time length being for example 20 seconds.

In one example, it was found that such a temperature profile, in particular by continuing to heat the aerosol generating substrate to between 230° C. and 260° C. during the vaping time, in combination with the pressure applied by the protrusions, can improve delivery of nicotine from a tobacco substrate by 50%, in one case increasing nicotine delivery from 0.462 mg per rod-shaped portion to 0.708 mg per rod shaped portion. At the same time, where the aerosol former was vegetable glycerin, it was found that glycerin delivery increased from 2.843 mg per rod-shaped portion to 4.718 mg per rod-shaped portion, and hence the quantity of aerosol produced was also substantially increased.

The tobacco rod was inserted into a Borgwaldt automatic smoking machine in an environment of room temperature 22° C., relative humidity 60%, wind speed 0.2 m/sec, and Health Canada Intense smoking method (puff volume 55 cc/2 sec, puff time 2 sec, a puff interval of 30 sec, and smoking 8 times.) The air dilution perforations were not closed. The mouth end of the tobacco rod was set in the automatic smoking machine, and the device was switched on. When the completion of preheating was detected by a signal (vibration) of the device, the first puff operation was performed. Thereafter, the puff operation was performed at intervals of 30 seconds. A Cambridge filter (Borgwaldt, 400 Filter 44 mm) was used for collecting particulate components in mainstream smoke. For the particulate components, calculate the TPM (particulate component: Total Particular Matter) amount from the weight change of the Cambridge filter. After extraction with shaking with 10 mL of isopropanol for 20 minutes, water, nicotine, and glycerin levels were measured and by using GC-FID/TCD (6890N, Agilent).

In FIG. 1A, the consumable 1 comprises a filter 14 which can be used as a mouthpiece by a user for inhaling the generated aerosol. However, in other embodiments, the consumable may not be designed for a user to inhale aerosol directly. For example, the consumable 1 may be entirely enclosed within a device 2 which generates the aerosol and provides the aerosol through a separate outlet or mouthpiece.

In some embodiments, a length axis of the consumable 1 as a whole may differ from a length axis of the rod-shaped portion 11 which is inserted into the heating chamber 21. For example, the consumable 1 may comprise additional features not designed to fit in the heating chamber 21. In such cases, the length axis of the rod-shaped portion 11 is the axis which is relevant for identifying the resilient portion 12.

The term “heater” should be understood to mean any device for outputting thermal energy sufficient to form an aerosol from the aerosol substrate. The transfer of heat energy from the heater 54 to the aerosol substrate may be conductive, convective, radiative or any combination of these means. As non-limiting examples, conductive heaters may directly contact and press the aerosol substrate, or they may contact a separate component such as the heating chamber which itself causes heating of the aerosol substrate by conduction, convection, and/or radiation.

Heaters may be electrically powered, powered by combustion, or by any other suitable means. Electrically powered heaters may include resistive track elements (optionally including insulating packaging), induction heating systems (e.g. including an electromagnet and high frequency oscillator), etc. The heater 54 may be arranged around the outside of the aerosol substrate, it may penetrate part way or fully into the aerosol substrate, or any combination of these. For example, instead of the heater of the above-described embodiment, an aerosol generation device may have a blade-type heater that extends into an aerosol substrate in the heating chamber.

The term “temperature sensor” is used to describe an element which is capable of determining an absolute or relative temperature of a part of the aerosol generation device 2. This can include thermocouples, thermopiles, thermistors and the like. A temperature sensor may be provided as part of another component, or it may be a separate component. In some examples, more than one temperature sensor may be provided, for example to monitor heating of different parts of the aerosol generation device 2, e.g. to determine thermal profiles. Alternatively, in some examples, no temperature sensor is included; for example, this would be possible where thermal profiles have already been reliably established and a temperature can be assumed based on operation of the heater 22.

Aerosol generating substrate includes tobacco, for example in dried or cured form, in some cases with additional ingredients for flavouring or producing a smoother or otherwise more pleasurable experience. In some examples, the substrate such as tobacco may be treated with a vaporising agent. The vaporising agent may improve the generation of vapour from the substrate. The vaporising agent may include, for example, a polyol such as glycerol, or a glycol such as propylene glycol. In some cases, the substrate may contain no tobacco, or even no nicotine, but instead may contain naturally or artificially derived ingredients for flavouring, volatilisation, improving smoothness, and/or providing other pleasurable effects. The substrate may be provided as a solid or paste type material in shredded, pelletised, powdered, granulated, strip or sheet form, optionally a combination of these. Additionally, the aerosol substrate may comprise a liquid or gel.

The aerosol generation device 2 could in some embodiments be referred to as a “heated tobacco device”, a “heat-not-burn tobacco device”, a “device for vaporising tobacco products”, and the like, with this being interpreted as a device suitable for achieving these effects. The features disclosed herein are equally applicable to devices which are designed to vaporise any aerosol substrate.

The aerosol generation device 2 may be arranged to receive the aerosol substrate in a pre-packaged substrate carrier. The substrate carrier may broadly resemble a cigarette, having a tubular region with an aerosol substrate arranged in a suitable manner. Filters, vapour collection regions, cooling regions, and other structure may also be included in some designs. An outer layer of paper or other flexible planar material such as foil may also be provided, for example to hold the aerosol substrate in place, to further the resemblance of a cigarette, etc. The substrate carrier may fit within the heating chamber 11 or may be longer than the heating chamber 11 such that the lid 25 remains open while the aerosol generation device 2 is provided with the substrate carrier. In such embodiments, the aerosol may be provided directly from the substrate carrier which acts as a mouthpiece for the aerosol generation device.

As used herein, the term “fluid” shall be construed as generically describing non-solid materials of the type that are capable of flowing, including, but not limited to, liquids, pastes, gels, powders and the like. “Fluidized materials” shall be construed accordingly as materials which are inherently, or have been modified to behave as, fluids. Fluidization may include, but is not limited to, powdering, dissolving in a solvent, gelling, thickening, thinning and the like.

As used herein, the term “volatile” means a substance capable of readily changing from the solid or liquid state to the gaseous state. As a non-limiting example, a volatile substance may be one which has a boiling or sublimation temperature close to room temperature at ambient pressure. Accordingly “volatilize” or “volatilise” shall be construed as meaning to render (a material) volatile and/or to cause to evaporate or disperse in vapour.

As used herein, the term “vapour” (or “vapor”) means: (i) the form into which liquids are naturally converted by the action of a sufficient degree of heat; or (ii) particles of liquid/moisture that are suspended in the atmosphere and visible as clouds of steam/smoke; or (iii) a fluid that fills a space like a gas but, being below its critical temperature, can be liquefied by pressure alone.

Consistently with this definition the term “vaporise” (or “vaporize”) means: (i) to change, or cause the change into vapour; and (ii) where the particles change physical state (i.e. from liquid or solid into the gaseous state).

As used herein, the term “atomise” (or “atomize”) shall mean: (i) to turn (a substance, especially a liquid) into very small particles or droplets; and (ii) where the particles remain in the same physical state (liquid or solid) as they were prior to atomization.

As used herein, the term “aerosol” shall mean a system of particles dispersed in the air or in a gas, such as mist, fog, or smoke. Accordingly the term “aerosolise” (or “aerosolize”) means to make into an aerosol and/or to disperse as an aerosol. Note that the meaning of aerosol/aerosolise is consistent with each of volatilise, atomise and vaporise as defined above. For the avoidance of doubt, aerosol is used to consistently describe mists or droplets comprising atomised, volatilised or vaporised particles. Aerosol also includes mists or droplets comprising any combination of atomised, volatilised or vaporised particles. 

1. An aerosol generating system comprising: a consumable comprising a rod-shaped portion containing aerosol generating substrate; a heating chamber comprising a first end, a second end and a side wall extending around the heating chamber between the first and second ends, the heating chamber being configured to receive the rod-shaped portion of the consumable; and a heater configured to deliver heat to the heating chamber from the side wall, wherein: a width of the heating chamber is greater than a width of the rod-shaped portion, the consumable comprises a resilient portion around a length axis of the rod-shaped portion, the heating chamber further comprises a plurality of inward protrusions extending from the side wall and distributed around an inner perimeter of the heating chamber, and the plurality of inward protrusions are configured to engage with and apply pressure to the resilient portion in order to position the consumable within the heating chamber.
 2. The aerosol generating system according to claim 1, wherein the plurality of inward protrusions are configured symmetrically relative to the length axis to assist positioning the consumable at a center of the heating chamber.
 3. The aerosol generating system according to claim 1, wherein the first end of the heating chamber is open to receive the rod-shaped portion and the second end of the heating chamber is closed.
 4. The aerosol generating system according to claim 1, wherein, when the resilient portion is compressed perpendicular to the length axis of the rod-shaped portion by a force of 0.4N, the consumable exhibits a strain ratio of below 10%.
 5. The aerosol generating system according to claim 1, wherein, when the resilient portion is compressed perpendicular to the length axis of the rod-shaped portion by a force of 8N, the consumable exhibits a strain ratio of below 15%.
 6. The aerosol generating system according to claim 1, wherein, when the resilient portion is compressed perpendicular to the length axis of the rod-shaped portion by a force of 0.4N, the consumable exhibits a strain ratio of between 1% and 8%.
 7. The aerosol generating system according to claim 1, wherein the rod-shaped portion comprises a wrapper surrounding the aerosol generating substrate, and the resilient portion comprises a portion of the wrapper.
 8. The aerosol generating system according to claim 7, wherein the wrapper comprises cellulose paper or cellulose paper layered with aluminium foil.
 9. The aerosol generating system according to claim 1, wherein the aerosol generating substrate comprises tobacco.
 10. The aerosol generating system according to claim 9, wherein the aerosol generating substrate comprises randomly oriented tobacco strands containing tobacco powder and an aerosol former.
 11. The aerosol generating system according to claim 10, wherein the tobacco strands have a substrate density of between 0.3 mg/mm³ and 0.6 mg/mm³.
 12. The aerosol generating system according to claim 10, wherein the aerosol generating substrate comprises between 60 and 85 wt. % of tobacco lamina and between 8 and 20 wt. % of the aerosol former and between 5 and 15 wt. % of filler, based on a total weight of the aerosol generating substrate.
 13. The aerosol generating system according to claim 9, wherein the aerosol generating substrate is a compressed tobacco substrate or a mousse.
 14. The aerosol generating system according to claim 9, wherein the heater is configured to heat an interior of the heating chamber to at least 190° C.
 15. The aerosol generating system according to claim 14, wherein the heater is configured to heat the interior of the heating chamber to between 230° C. and 260° C.
 16. The aerosol generating system according to claim 14, wherein the heater is configured to maintain the interior of the heating chamber at at least 190° C. for a predetermined puff sequencing time.
 17. The aerosol generating system according to claim 1, wherein the plurality of inward protrusions are ribs extending along the side wall parallel to the length axis of the rod-shaped portion when the rod-shaped portion is received in the heating chamber.
 18. The aerosol generating system according to claim 17, wherein the aerosol generating substrate is arranged in a predetermined section of the rod-shaped portion extending along the length axis, and a length of the ribs is at least 50% of a length of the predetermined section.
 19. The aerosol generating system according to claim 18, wherein the length of the ribs is between 60% and 70% of the length of the predetermined section. 